The manufacture of a rifled barrel. The birth of a barrel, the manufacturing process in pictures How to make a rifled barrel at home

The barrel manufacturing technology directly affects the quality and properties of the resulting products. It is quite obvious that the materials used, tools and methods for manufacturing barrels determine the state of trace-forming surfaces, which ultimately affects the morphology of traces on a fired bullet, and also determines the individuality of the microrelief of these traces.

Therefore, we believe it is necessary to consider the features of the main operations and methods for manufacturing table channel rifling in a forensic aspect.

The process of manufacturing a rifled barrel firearms has more than two hundred different technological operations for machining barrel blanks, the formation of barrel channels, their chromium plating, thermal and chemical processing.

Among the main operations for the manufacture of trunks, the following can be distinguished: obtaining blanks; channel formation; making cuts; manufacture of a chamber; chrome plating of the barrel and chamber; external processing; edit .

Special high-quality carbon and high-alloy steels are used as materials for barrel blanks, which have high strength, elasticity, toughness, and corrosion resistance. The composition of barrel steels includes iron, carbon and various alloying additives: manganese, chromium, nickel, molybdenum, etc. The mechanical characteristics of the main barrel steels are shown in Table 1.

Table 1

steel grade	Hardness		Yield strength G		Tensile strength
	HRC	HB	MPa	kgf/mm 2	MPa	kgf/mm 2
50A	21-30	217	539	55	784	80
50RA	21-30	217	539	55	784	80
30HN2MFA	37-42	269	1273	130	1567	160
30XRA	37-44	241	1273	130	1567	160

Steel grades 50A and 50RA are used for the manufacture of barrels with a caliber of up to 9 mm with a low rate of fire (rate of fire) - up to 600 rounds per minute. Sometimes, to increase ductility, toughness and durability, steel is refined with synthetic slags. However, this causes certain difficulties in removing chips and providing the necessary surface roughness. Despite the fact that this circumstance is a negative production factor, it favorably affects the formation of the microrelief of the surfaces of the bore, which is displayed in the traces on the bullet.

Steel grades 30XRA and 30KhN2MFA are used for barrels up to 23 mm caliber with an average rate of fire (up to 1,500 rounds per minute), and for barrels 30 mm or more with a high rate of fire (over 1,500 rounds per minute), OKHN3MFA steel is used. The first letter "O" means that the steel is weapon-grade.

From a technical point of view, the bore of a weapon is a deep hole (the ratio of the length of the bore is no less than five times its diameter).

In the workpiece, the channel is usually made according to the scheme: preliminary solid drilling, semi-finish reaming, fine reaming or honing, sometimes electrochemical processing, sometimes broaching.

Solid drilling is carried out with special deep-hole drills, the so-called gun drills. A feature of such drills is the V-shape of the cutting part and the same shape of the stem (for external chip removal).

Semi-finishing and finishing reaming of channels after drilling is carried out with reamers made of tool steels or with knives equipped with hard-alloy plates.

Honing of channels is carried out by honing heads with one bar for small diameters (4-6 mm) and multi-row for large ones (8-30 mm).

At some enterprises, pulling the channels of the barrel pipes is used. This operation is carried out with a special tool - broach. With this broach, translational or translational-rotational motion is reported. With the translational movement of the broach, longitudinal risks are formed on the channel surface, a certain part of which can remain after finishing the bore and, therefore, form part of the structure of the microrelief of the channel surface, which is displayed in the marks on the bullets.

The formation of rifling in the bore is traditionally considered the main operation that determines the entire technological process of manufacturing the barrel. Therefore, the quality and economy of the manufacture of the barrel is usually associated with the method of obtaining rifling.

Of the old ways of shaping grooves, trellis planing still finds application. This process is unproductive, but is used due to the straightness of the treated surfaces in the manufacture of sports and sniper weapons.

The processing of rifling with a trellis takes place on a trellis machine. During the working stroke, the trellis is inserted into the channel of the treated trunk and is given translational and rotational movement. The addition of these movements gives a trajectory corresponding to the steepness of the rifling. Cutting chips to the required depth of cut is carried out in several passes with special cutters - hooks or brushes. Single-hook tapestries (Fig. 18) and multi-brush tapestries (Fig. 19) are used.

Rice. 18. The design of the hook trellis: 1 - tube; 2 - hook (cutter);

Rice. 19. Design of a multi-brush trellis: 1 - wedge; 2 - brush;

3 - tube.

The manufacture of the guide part of the bore by planing with a trellis eliminates the blunting of the edges of the combat and idle edges of the rifling, which is important for achieving uniform movement of the bullet along the barrel.

When planing rifling with a trellis, as a result of wear of the cutting parts of the brushes and foreign particles entering the cutting zone, the following defects may form in the bore:

- "streaming", that is, longitudinal scratches arising from metal particles adhering to the cutting edges of the trellis cutters;

- "valances" - ledges of the planes of the edges of the rifling;

Shortage of edges - different heights of the edges of the rifling;

The collapse of the edges - the non-parallelism of the edges of the rifling.

The listed defects are displayed in traces of rifling, combat and

idle edges of rifling, giving them a peculiar character: due to the striation, lines are formed in the traces of the bottom of the rifling, gaps and a lack of edges affect the configuration of the profile of prints of combat and idle edges, traces of rifling fields.

Among the obsolete methods of shaping rifling, the method of pulling rifling should be mentioned.

The channel is drawn with a special tool - a broach, on which teeth are made corresponding to the profile of the grooves. Cutting the metal to the required depth occurs in several broach passes. The kinematics of rifling pulling, in addition to the longitudinal movement of the tool, must have the rotation of the workpiece or broach in accordance with the steepness of the rifling.

In general, the surface defects of the bore, which are formed during the formation of rifling by pulling, and the features of their display in traces on bullets are similar to those described above.

The mandrel method consists in pulling a mandrel - a special punch - through the bore. The diameter of the mandrel is slightly larger than the diameter of the trunk. Moreover, on the mandrel there are protrusions according to the number of grooves with sizes and slopes corresponding to the grooves. This method is based on the ability of the metal to deform under the action of the protrusions of the punch to form the rifling. When passing through the bore, the mandrel squeezes out the profile of all the rifling at once. The design scheme of the mandrel is shown in fig. twenty.

This method of rifling gives a high surface quality, but often leads to a change in the shape of the channel with a changeable profile of the outer surface and uneven structure of the material after heat treatment of the barrel billet.

Rice. 20. Structural scheme of the mandrel: 1 - guide part; 2 - lead-in (intake) cone; 3 - calibrating part; 4 - rear cone; 5 - shank;

a - protrusion; b - depression.

Depending on the nature of the stresses experienced by the mandrel, two schemes of mandrel are distinguished: "in tension" (pulling the mandrel) and "in compression" (pushing the mandrel).

During “tensile” burnishing, the tool stem experiences tensile and torsion deformation. When mandrel "in compression" (Fig. 21), the stem of the mandrel experiences compression and buckling deformation. This scheme is most used when forming a complete profile of grooves and fields in one pass of the mandrel.

Rice. 21. Scheme of mandrel "in compression" (pushing the mandrel): 1 - mandrel head; 2 - mandrel stem; 3 - stem blank.

After burnishing, defects may occur in the form of longitudinal scratches from metal particles adhering to the surface of the punch; waviness of the fields and rifling formed due to the different hardness of the metal and the unequal thickness of the copper coating of the guide surface of the bore (before burnishing, the bores are coppered); transverse scratches caused by reaming before burnishing. It is quite obvious that these defects show up appropriately in the marks on the bullets.

Using the process of electrochemical processing (ECM) allows you to get almost a single design of the bore.

The ECHO method is based on the use of the process of anodic dissolution of metal, not protected by insulators, at a certain electrolyte flow rate. The rifling of the barrel bore is made using a cathode that includes a conductive body, on the surface of which there are screw insulators made of plexiglass, which protect the fields from anodic dissolution and simultaneously center the cathode in the bore (Fig. 22).

Rice. 22. Structural scheme for electrochemical processing of rifling:

1 - hose; 2 - cathode contact; 3 - barrel (anode); 4 - cathode; 5 - anode contact;

6 - hose for draining liquid.

The cathode is a steel or brass rod with helical grooves milled on its outer surface with a rifling pitch in the bore. Insulating inserts made of plexiglass or ebonite are placed in the grooves. The number of grooves is equal to the number of rifling in the bore. Through the use of the ECHO method it is possible to obtain high quality surfaces. The formation of defects on the trace-forming surface of the barrel bore is possible only if there is a corresponding defect on the cathode.

The use of the method of radial compression (forging) due to its sufficiently high productivity is the most widespread.

The essence of the process of radial compression is the strict symmetrical compression of the workpiece with a mandrel located inside it.

There are two ways of radial reduction: with cold and hot process. Hot radial reduction is used in the manufacture of thin-walled tubular parts (blanks of hunting rifle barrels) and large-sized parts ( artillery systems). With cold radial compression, a higher accuracy and quality of machined parts is achieved, which makes it possible to use this method for the manufacture of rifled barrels.

With radial compression, stresses arise that change the dimensions of the channel. So, when forming the muzzle of the channel in the form of a precisely set outlet chamfer and a safety bore, a bell or compression inevitably occurs, that is, an increase or decrease in the size of the channel in the direction of the muzzle. This defect affects the deterioration of the accuracy of fire and affects the display of traces formed on the bullet during the shot by the previous sections of the surface of the bore, which was revealed

experiments by A.I. Ustinova and E.I. Stashenko. In addition, mandrel surface defects, various foreign particles adhering to it, due to the ductility of the barrel blank metal, can appear on the channel surface, which in turn will directly affect the features of the character of the bore marks on the bullet.

The domestic industry has accumulated experience in the manufacture of rifled weapons based on the combined method of obtaining barrel channels using trellis processing and burnishing in a different form, in which they are usually used in barrel production. The straightness of the surface of the bore is ensured during preliminary operations by smooth planing with a trellis with a long reciprocating motion without metal removal and the subsequent formation of fields and grooves by means of a set of movable cathodes with a profiled conductive part, which makes it possible to eliminate such surface defects in the manufacture of barrels from 30KhN2MFA steel, which after

trellis treatment caused a deterioration in the quality of the canal.

The quality of the surface treatment of the bore is the determining factor, which determines the degree of expression of the microrelief in its traces on the bullets. The state of the surface roughness of fields and rifling is evaluated in two directions: along the rifling, that is, in the direction of the bullet, and perpendicular to the rifling. In accordance with this, the surface roughness index, determined perpendicular to the progress of the rifling, is taken two digits higher than along the rifling (for example, the roughness values ​​R for pistols, machine guns and rifles along the fields and rifling, as well as perpendicular to the fields and rifling are 0.32 µm and 0.63 µm, respectively).

Barrel chambers are made in two ways: in one case, the chamber is formed in the process of radial forging, in other cases, the chamber is made by reaming a set of shaped reamers.

In the latter version, the manufacture of chambers consists of several stages: pre-processing, finishing and final finishing. Pre-treatment is performed before the formation of grooves in the bore, the operation of finishing - after the formation of grooves, and the final finishing is carried out at the end of the technological manufacture of the barrel.

Preliminary processing consists in the formation of the first and second cones of the chamber, finishing - in the formation of the third and fourth, and the final - the bullet entry and all the cones of the chamber.

Such a sequence of operations for processing the chamber is determined by special requirements for the alignment of the elements of the chamber with the guide part of the bore. In this regard, when finishing and finishing the chamber, on which its coaxiality depends, the barrel channel after the formation of rifling in it serves as the base mounting surface.

The presence of even a slight misalignment of the chamber with the bore will be directly reflected in the nature of the traces on the fired bullets - the positions of the lines of the beginning of the primary and secondary traces, the presence of traces of the initial contact of the bullet with the walls of the bore.

After operations for the manufacture of a channel and a chamber in an automatic weapon, to increase its survivability and storage time, chromium plating of the barrel channels and chambers is carried out. Chrome plating is carried out electrolytically.

The final operation in the manufacture of the bore is its lead (noise), when the barrels are roughened to a mirror finish.

The tool is a ramrod with a lead head mounted on the end, called a shust. Shust in diameter is made in the size of the caliber of the barrel, and in length about ten calibers. The noise is pushed with force along the plane on which the abrasive powder is poured. In this case, the abrasive grains caricature the cylindrical surface of the burr and, when the burr reciprocates along the channel, polishes it.

During this operation, the initial width of the grooves changes within tolerances, depending on how significant the defects being eliminated are.

In the course of borehole noise, the final “production” formation of the microrelief of its surface occurs, all further changes in the trace-forming surfaces of the bore will already be determined by operational factors.

In concluding this paragraph, it is important to note that both from a technical and forensic point of view, the presence of a barrel in the design of an object is one of the characteristic features and a determining condition for its classification as a firearm.

A functional analysis of the elements of the shaft structure made it possible to identify the significance of each specific element in the mechanism of trace formation, which will allow us to further build a logical scheme of the trace formation process.

The study of the main technological operations for the manufacture of the bore contributed to the identification of the features of various production methods that determine the final morphological state of the trace-forming surfaces of the bore. In other words, there is a direct connection between the methods used for making barrel bores and the tools chosen for this with the mechanism for the formation of marks on fired bullets and individual features these traces.

So, the use of mechanical methods for making rifling (planing with a trellis, pulling, mandrelling) leads to the formation of a relief structure in the bore (streaming, gaps, etc.), and various other microdefects that are displayed in dynamic traces on bullets. The use of the electrochemical method of manufacturing trunks is less favorable for creating prerequisites for the formation of microrelief traces.

The presented material leads to the conclusion that when studying the trunk as a trace-forming object, it is necessary to adhere to an integrated approach - to take into account design features and technological processes in conjunction with the forensic theory of reflection. A complex approach to the study of the trunk as a trace-forming element is important in the process of proving involvement small arms to the event of a crime, as it directly increases the reliability and validity of the conclusions of the study.

More on the topic Manufacturing of barrels of rifled firearms.:

1. The evolution of legal development and the main classification of firearms
2. Ammunition for firearms and their characteristics
3. Information and communication bases for comparing firearms.
4. § 1.1. Conceptual foundations of forensic research of rifled firearms by traces on bullets
5. § 1.2. Theoretical foundations of forensic ballistic identification of rifled firearms by traces on bullets
6. § 1.3. Classification of the tasks of forensic research of rifled firearms according to traces on bullets
7. § 2.1. The barrel of a rifled firearm as a trace-forming object
8. Manufacture of barrels of rifled firearms.
9. Classification and design of modern bullets for rifled small arms.
10. § 2.3. Periods of a shot and the mechanism for the formation of traces of a rifled bore on bullets

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Select the type of steel for the gun barrel. It must withstand a pressure of 100,000 psi (pound force per square inch) (689476 kPa) to withstand the pressure of the gases pushing the bullet. The steel must have a hardness of 25-32 on the Rockwell scale to withstand the pressure required to push the cartridge through the barrel, and not be so weak as to be damaged during the operation of the mechanism. Buy high quality 32mm thick barrels from a steel mill. Demand that you be given a certificate of quality, and say that the steel must be subjected to stress relief.

• Choose 4140 chromoly steel, which is the cheapest option. It is also easier to chemically paint it black if you want to give the barrel a traditional look.
• You can also choose 416 stainless steel. It is more expensive than chrome molybdenum steel. Stainless steel barrels last longer and are more accurate than chromoly steel shotguns.

Cut out the base for the trunk of the required length (72-76 cm). The ends of the barrel should be parallel to each other, perfectly round and ground.

Drill a hole. It should run inside the entire length and be 0.1 mm smaller than the desired hole diameter. To do this, you need to use a special tool - a drill for deep drilling. When working with such a drill, the tungsten carbide head will be stationary and the barrel will rotate to drill the hole. Drilling will take place with liquid cooling and at a speed of 25 mm per minute. Drilling the hole completely will take about 30 minutes.

Expand the hole. Go through the hole with a tungsten carbide reamer using coolant. The reamer will widen the hole to the desired size and smooth it out from the inside as it is used to correct the bore.

Make a stem cut. It is a screw grooves (grooves) in the hole, due to which the bullet, passing through the barrel, will begin to rotate. As a result, the flight of the launched bullet will be stabilized by rotation. Decide on the number of rifling along the bore and the desired number of bullet revolutions. Consult on these issues with specialists in the manufacture of gun barrels, which you can find in gun stores.

• Make the first groove. Insert the cutter into the hole and run it through the channel, rotating the barrel as recommended by the specialist to get the desired cut and charge rotation rate.
• Add more grooves. For the next recess, return the barrel to its original position. Run the cutter inside the channel, rotating the barrel as recommended by the specialist to get the desired rifling and charge rotation rate.
• Finish cutting. Make as many grooves as you need.

The project of building a factory for the production of rifles arose quite recently in 2008, and the first product saw the light of day just two years ago in March 2011. The plant was built almost from scratch, initially in its place there were premises in a monstrous state. May 15, 2010 began overhaul. Production flagship - sniper rifle ORSIS is short for "weapon systems". But we will return to the history of the plant, and now let's go inside.

My path passes through a shop where trunks are processed. The workpiece in which a hole will be drilled and cutting will be made is called a "blank". Forms are delivered to the factory from the USA.

On such machines, parts for rifles are processed. Here, a hole is first drilled in the blanks, the width of which depends on the caliber of the future rifle. Some machines, by the way, were designed in design office plant with the assistance of consultants from Switzerland and Germany.

In general, the plant has more than 30 machine tools for various purposes with numerical control (CNC). They are very different, there are simpler ones, for simple operations, and there are those that do really unique things, using technologies that I heard about for the first time.

The barrels are made of special gun grade stainless steel.

Notice the coin. She stands with an edge on the moving part of the machine, which cuts the barrel from the inside. The smoothness and accuracy of the course during this operation is so high that it does not allow the coin to fall. At the end of the post you can see a video of this process.

The same machine. Here you can see how a rod descends into the blank of the barrel, making rifling - 4-6 spiral stripes, they help stabilize the trajectory of the bullet. Cutting is done with a special-shaped metal hook, which is also manufactured at the factory.

The tool enters the stationary workpiece and leaves a one micron deep cut mark. Oil is poured onto the barrel to facilitate cutting. The process of cutting the trunk lasts 3-5 hours. For one cut, the tool must go inside 60-80 times. After that, the barrel is manually polished with lead-tin lapping and cleaned of oil.

After these operations, the barrel enters the laboratory.

Here, specialists probe the bore with a borescope (a relative of the endoscope) for defects - scratches, shells or cracks. The barrel is checked several times: after drilling a hole, cutting and polishing.

What kind of firewood we will find out a little later.

A blank, which will soon become the main part of the shutter mechanism.

The CNC machine processes the part of the shutter mechanism, which is immediately cooled with water.

General plan of the second workshop.

For each model they make their own bed. It provides structural rigidity. For tactical rifles, an aluminum stock is used, for sports rifles - from a special weapon laminate. In addition, the factory makes the bed from valuable breeds wood, such as walnut.

The machine also works on program control.

One blank of this part can cost several tens of thousands of rubles. If you look closely at one of these bars, you will notice 4 layers of plywood or, as it is called in another way, wood laminate.

After processing on a milling machine, craftsmen manually grind it, apply branded notches with a laser and impregnate it several times with oil. For one shift, the master makes 2-3 beds.

A recess is made in the blank for the barrel, after which it is once again covered with oil and only then with varnish.

Here you can see how the blanks are polished.

And in the next room, a small discovery awaited me.

Here, with the help of high-precision equipment (the cost of which is estimated at tens of thousands of euros), parts for the bolt group (triggers, fuses, triggers) that could not be done with other machines.

Details are cut using electrical erosion technology. Here is such a thread, it can be made of molybdenum or brass.

Everything happens like this: the thread from the spool is threaded through a small hole in a metal sheet or blank, fixed from below so that it can be wound on another spool. This sheet is then immersed in a bath of water into which a high voltage and power current is applied.

The thread is quickly wound on the second spool and the machine thus cuts out details that are highly accurate down to microns. This process may take 3-4 hours. Such a modernized jigsaw.

Here, too, CNC, a person only sets programs and monitors the accuracy of the operation.

Here from this blank

the excess is cut out so that another part can be inserted.

And I was also surprised that the thread can cut at an angle. Here, a part is cut out from the middle of this cylinder, which is round on one side and asterisk-shaped on the other.

Trigger details.

Here you can see that several sheets were welded together in order to cut out the maximum number of parts.

We leave this workshop and head to the assembly area, this is the last stage before the rifle gets into the shooting range.
In these boxes are ready-made rifles.

The specialist brings together the parts of the action group, attaches them to the barrel, after which the glass bedding process follows. A special mastic is applied to the rifle stock, metal parts are placed in it and left for a day until completely dry. Then the parts are taken out again and given for painting, and their exact imprint remains on the bed, which allows you to fit the wood to the metal. This provides greater accuracy to the weapon.

After painting, the parts are put back together. Specialists of the technical control department inspect the finished product and give a conclusion that the rifle is ready to fire.

There are also very young workers at the plant.

Every day, the factory produces up to 10 rifles a day.

In addition to rifles, the factory assembles Austrian rifles under license. Glock pistols different calibers.

And this is a refrigerator, but in it you will not find vegetables, fruits, beer, yesterday's dinner and other snacks. It is also used in the assembly of the rifle. How, you ask?

The fact is that when assembling some parts, it is necessary to screw some parts to the bed as tightly as possible. If this is done at room temperature, then the screws will cut too hard into the product and can ruin it, so these parts are placed in the refrigerator for a while so that it shrinks a little (I hope everyone remembers physics) and can be screwed as tightly as needed, without risk of damaging the bed.

The stages of folding the tube of a simple trunk.
Above - a blank plate for the barrel

Probably, many will agree with me that the main part of the gun is the barrels. After all, they are the ones who shoot. The effectiveness of cannon shots made a person want to make a small "hand" cannon. Such a cannon was found in the Tanneberg castle in Hesse (Germany) in the middle of the century before last. It was cast at the end of the 14th century. It was, of course, difficult and inconvenient to shoot from it with hands, and soon a crossbow box was adapted to it. It turned out that in terms of shooting accuracy and accuracy, the new weapon is seriously inferior to a good bow, although it significantly surpasses it in terms of energy, and hence penetrating power. It quickly became clear that with an increase in the length of the barrel, the shots become more accurate. From this moment begins the history of firearms.

Today, our "turning point" hunting rifle has three main parts: the barrel (or barrels that form the barrel block), block, bed.

The barrel gives direction to the flight of shot or bullets. The more correctly and carefully it is made, the better the shot scree and the higher the accuracy.

The block locks the breech section of the barrels, serves as a connecting element between the barrels and the stock, and is the main inertial element in the weapon that absorbs the recoil force. Locking, trigger and safety mechanisms are mounted in the block.

The stock ensures the convenience of aiming the weapon at the target, the naturalness of aiming and softens the effect of the recoil force due to its partial transformation into a rotational moment.

Before talking about today's technology for manufacturing gun barrels, I would like to acquaint readers with a part of the history of weapons related to the improvement of the manufacture of this most important part of the weapon. After all, to make a good barrel is a rather difficult task even at the current level of development of mechanical engineering. However, the perseverance, diligence and ingenuity of our distant ancestors found various options for solving this problem. And the level of quality the best products The 18th century seems almost mysterious to today's specialists. We want to tell how the masters of the past created wonderful weapons, show some of their samples and think together about the greatness of their spirit with the hope that this will strengthen our own.

In 1811, Heinrich Anschütz (from a well-known weapons dynasty) published a book about the weapons factory in Suhl. He writes about four types technologies for obtaining receiver tubes: ordinary, twisted, wound and trunks from "Damascus".

A conventional (simple) barrel was made from a strip stock 32 inches (812.8 mm) long, 4 inches (101.6 mm) wide, 3/8 inch (9.525 mm) thick. After heating, this strip was bent by forging on a mandrel in such a way that its longitudinal edges adjoined to each other end-to-end, parallel to the axis of the bore. This joint was welded by the forge method and carefully forged. There are undoubted indications that both long sides of a rectangular billet were sometimes driven "on a mustache" and welded not end-to-end, but overlapped. After welding and cooling, the barrels were reamed with a tetrahedral reamer, the outer surface was turned on a lathe, which was then manually ground on a large circle of soft sandstone with a diameter of 1.75 m. A screw plug was screwed into the barrel from the breech side, which was sometimes also boiled. Of course, the barrels of all muzzle-loading guns were “muffled”, regardless of the technology for their production.

Twisted stem. A weld in a conventional barrel, located parallel to the axis of the barrel, was often the site of destruction during firing. To avoid this, a simple welded barrel was started to be reheated in the central part and twisted along the axis along the entire length so that the weld was in the form of a helix. This technique made the seam much less loaded when fired.

A coiled barrel was obtained by gradually winding a steel strip onto a mandrel in the form of a rod or pipe. The helical weld was sequentially forged with a blacksmith's hammer.

Damascus stems. Back in the Middle Ages, swords of exceptionally high quality were made in Damascus (today it is Syria). As soon as the technology for their production became clear to Europeans, they tried to apply it to the manufacture of trunks. The basis of the secret was that blanks for bladed weapons were obtained by forge welding strips of thin elements consisting of steels differing in carbon content. The initially welded and forged strip was repeatedly folded and forged. Compared with the usual homogeneous blank, Damascus had three fundamental advantages. In fact, it was a design that combines the properties of individual materials. In addition, the composition not only eliminated internal defects that occur in a homogeneous workpiece, but also created an optimal structural orientation. In principle, Damascus trunks were obtained by winding. However, to obtain the original strip had to do just a titanic work. First, a bar was welded from a hundred bars of steel different composition square section with a side of 0.7 mm, laid in a certain order. The bar was obtained with a section of about 7 mm x 7 mm. This procedure required an incredibly fine blacksmith's sense, since it was easy to burn through thin wires. The welded bar was again heated and twisted along. Then they took several such twisted bars (usually three or six), welded them together and forged them into a strip. In some cases, something like braids were woven from these twists, which could consist of a different number of strands and have a different weaving pattern. Pigtails were welded and forged into a strip. This strip was wound onto the mandrel. Then the workpiece was faceted, the channel was reamed, the outer surface was first turned on a lathe, then polished. The bluing process in those days consisted in processing with rather strong acids. As a result, low-carbon twigs were etched much more strongly than high-carbon ones, and an original small pattern appeared on the surface of the trunk, reflecting the entire previous striping scheme. Usually on Damascus trunks, the width of the band is visible to the naked eye.

The rapid development of metallurgy at the end of the 19th century led to the emergence of carbon steels with high mechanical properties. The prospect of their use for the manufacture of trunks seemed obvious. However, back in the first quarter of the 20th century, many gunsmiths in Europe continued to make barrels using “Damascus technology”. Today it is necessary to understand that such barrels, although they are monuments to the fantastic zeal of gunsmiths of previous generations, are still inferior in all important indicators to modern alloyed barrel steels. Let us remind our compatriots that steel 50A and even 50RA, from which trunks are made today both in Tula and Izhevsk, do not belong to alloyed barrel steels. And more about Damascus trunks. A hundred or more years after manufacture, it is very likely that the forge welding of the elements may be significantly destroyed and the strength of the barrels may not be sufficient to ensure safe firing. Be very careful if you want to shoot with an old shotgun with Damascus barrels.

The introduction of chromium, vanadium, nickel, silicon, manganese and other elements into the composition of carbon steel has led to a significant increase in the most important properties of barrel steels - elasticity, tensile strength, surface hardness, corrosion resistance. Moreover, these technologies make it possible to obtain steels with predetermined properties. All this made it possible to proceed to the manufacture of homogeneous blanks for gun barrels. This process began in the last third of the 19th century and coexisted with the "Damascus" technology for about half a century.

The development of technology for the manufacture of gun barrels.

The new stage begins with the rejection of trunks obtained from the strips, and the transition to trunks, the channel of which was formed by deep drilling. This technology is incomparably more productive, but for its implementation it was necessary to solve a number of serious problems, which we want to talk about so that modern readers can imagine what the price was for guns with excellent action. New technology The manufacture of barrel blanks begins with forging, which not only gives the barrel blank an external shape that approximates the finished barrel, but also improves the structure of the steel by reducing its grain size. Usually, a piece of round steel with a diameter of about 50 mm is cut off for forging. The length of this blank depends on the future length of the barrel. A piece 320 mm long is enough to pull out a forged workpiece 750 mm long with an average diameter of 30 mm from it. Of course, after forging, the diameter of the workpiece in the chamber area is noticeably larger than that of the muzzle. It should be noted here that in conventional forging, about 15% of the steel goes into scale. Blacksmiths say that metal "burns out".

Weapon drill:
a - cutting plate,
b and c - guides,
d - channel for supply
coolant,
e - cavity for
chip removal

To relieve internal stresses in forged blanks, they are heated to (approximately) 850-860 degrees and kept for about half an hour. The exact heating parameters depend on the grade of barrel steel and the thickness of the workpiece. The task of relieving internal stresses is very important for all stages of barrel production. It is especially important that there is no tension in the finished receiver tube intended to form receiver blocks from two or more barrels. The fact is that soldering with soft and especially hard solders requires significant and asymmetric heating of the barrels. The cooling of the soldered block also occurs non-uniformly. The presence of internal stresses leads to a noticeable deformation of the trunks after soldering. Moreover, the high heating of the inner surface of the barrels during firing, especially intense shooting, can cause irreversible deformation of the barrel if stresses remain in it. After normalization, hardening is carried out. Its essence lies in obtaining optimal properties due to the formation of a fine structure of the metal. Any steel is a phase-complex system containing at least two crystalline modifications of pure iron, iron carbide, carbides of metal impurities and solid solutions of some of these components in each other. Thermal treatment changes the phase state of this complex system and the size of individual phases, which greatly affects the performance properties. Hardening consists in uniform heating of the part to a temperature that depends on the recipe of the steel from which it is made. Billets made of Sk 65 steel, which is often used for barrels in Germany, are heated to 840 degrees. After that, it is dipped in oil at room temperature. Then the workpiece is “released”, for which it is heated in a muffle furnace for about 4 hours at a temperature of 580-600 degrees. Such complex heat treatment can significantly affect the hardness, toughness, elasticity and tensile strength.

The heat-treated workpiece is carefully straightened. This is done so that when drilling, which occurs when the workpiece is rotated, it does not vibrate. The workpiece is straightened in a horizontal position during rotation, correcting its shape with pressure rollers. After straightening, the workpiece is again subjected to heating to relieve internal stresses, then it is faced on both sides and chamfered.

Straightening the trunk along the shadow rings
with a screw press

After that, they proceed to the most delicate process in the manufacture of the barrel - drilling. Deep drilling, especially in long workpieces with low longitudinal stability, is a special song. In the weapons business, special machines similar to lathes are used for this. In them, the fixed workpiece rotates, and the special drill moves forward. There are two main problems in this process: the removal of the drill from the axis of the workpiece and the removal of chips. The first problem can be solved due to the homogeneity of the structure of the workpiece and the relatively low feed rate of the drill and cutting speed in order to eliminate the vibration of the workpiece. Of course, these restrictions increase the drilling time. The problem of chip removal, which sometimes not only spoils the surface of the channel, but also jams the drill, is solved by special techniques. In the 19th century, “gun drills” were used, in design they were close to reamers, that is, they were based on a rod, along the entire working length of which a cylindrical sector with an angle of about 100 degrees was chosen. The design of the drill is quite simple and is well understood from the drawing. Through a small hole in the body of the drill, a cooling emulsion is fed into the cutting zone, which, along a groove parallel to the axis of the drill, carries away the resulting chips. Such machines have long become multi-spindle and fairly automated. This allows one worker to control drilling on multiple machines. However, this process does not guarantee a high degree cleanliness of the bore surface treatment. Shavings were often the main reason for this. In addition, drilling performance was low.

Beisner drill -
working and
back part

In 1937, Burgsmüller made a qualitative change in the drilling pattern. He proposed a vertical arrangement of workpieces and the direction of drilling from bottom to top for better chip removal. As the basis of the drill, he used a pipe, on the working head of which three guide plates were attached and one cutting one was welded. The cutting process occurs when cooled by compressed air, which is fed into the gap between the surface of the drill and the walls of the resulting hole. The chips did not contact the walls of the hole at all and, together with the air, were carried down. The significantly higher torsional moment that the "pipe" possessed compared to the profiled rod allows, in addition to obtaining good surfaces, to use more high speeds cutting and feeding.

In 1942, Beisner improved on this method. He returned the drilling machine to a horizontal position, proposed the use of oil as a coolant, and improved the drilling head. Oil was supplied under pressure into the gap between the drill and the resulting cylindrical surface and carried the chips through the central channel to a special collector. The surface was very smooth, to some extent due to polishing guides. However, after drilling, the bore is reamed.

Before proceeding with the processing of the outer surface of the trunk, it is straightened: the straightness of the channel axis is checked and, if necessary, straightened with a screw press. The correctness of the channel is checked by shadow rings, which each hunter can do himself. But the editing process requires not only good vision, but also great feeling metal that comes only with experience. The fact is that the trunk has elasticity. Therefore, if it straightens up under load, then after its removal it will partially return to its original state. An experienced master feels how much the trunk needs to be “bent” so that after the load is removed, it becomes impeccably correct.

Turning necks for lunettes:
1 - center, 2 - sliding sleeve,
3 - stand, 4 - neck for lunette

After the formation of the bore, another difficult task arises: turning the barrel from the outside. In this case, the main difficulty is to ensure that the center of the outer surface exactly coincides with the center of the bore. If this is not done, then the receiver tube will turn out to be of different walls. In addition, due to the large value of the ratio of the length of the barrel to its diameter, when turning the surface of the barrel, it must be fixed with two steady rests, for each of which the necks must first be machined. For the correct execution of this operation, a special clutch is installed in the middle of the barrel length, which allows you to properly hold the barrel by its raw surface when turning the necks for steady rests. When the necks are machined, the sleeve can be removed and the outer turning of the barrel along the copier can be performed. These turning operations may result in some deformation of the barrel. Therefore, the trunk is once again controlled by the shadow rings and, if necessary, straightened. Fine turning and grinding is carried out after the necks for the steady rests are ground separately. The final stage in the manufacture of receiver tubes is fine grinding, called honing in the gun business.

Scheme of rotational forging:
1 - heating by high frequency currents,
2 - start of forging, 3 - forging process,
4 - end of forging

A significant progress in the manufacture of gun barrels is their forging on a mandrel. Of course, the equipment for this process is not cheap. Therefore, the molding of trunks by forging is profitable only with large volumes of production. However, the savings in time and money are also significant. In the manufacture of trunks by rotary hot forging, blanks with a length of 260-280 mm and a diameter of about 35 mm are used. In it, a through hole with a diameter of 20.5 mm is made with a Beisner drill. The workpiece is fixed on a hardened, carefully polished mandrel, shaped like the inner surface of the finished barrel. After electric induction heating of the billet to the required temperature, it is fed into the forging zone, where it, rotating along its axis, passes under the blows of cross-shaped hammers. In a minute and a half, the workpiece takes the external and internal shape of the barrel with a chamber. Hardening after such forging is not carried out. The outer shape of the barrel is adjusted by turning and grinding. The bore is rough-drawn with a reamer. The final processing of the bore, including the chamber and choke, is carried out after the assembly of the barrel block.

An even more advanced method of manufacturing barrels is cold forging on a mandrel. One of its advantages is that it saves about 15% of expensive barrel steel that goes into scale during hot forging. In addition, the inner surface of the barrel is an exact copy of the mandrel, so that you can get completely finished barrels (with a chamber, choke and rifling). The surface of the bore requires only polishing. In addition, the structure of the cold forged barrel provides it with high mechanical properties. True, cold forging requires more powerful hammers and longer duration. It lasts just over three minutes. The outer shape is finished by turning and polishing. The correctness of the channel axis is also checked after this technology and, if necessary, straightened. The final stage in the manufacture of individual barrel blanks is shooting and branding.

Vladimir Tikhomirov
Master shotgun 10-2004

• Articles » Workshop
• Mercenary 28922 0

Many master classes on beaded trees are based on the fact that the trunk of the tree itself is made from twisted skeletal branches, but here we want to consider another option for making the base. The branches will be attached to the finished trunk. So, this master class is how to make a beaded tree trunk with your own hands in a step-by-step form with a photo.

For this we need: thick wire, building plaster or alabaster, a small bowl and a plate interesting shape slightly larger for the stand, foil, paper towel (toilet paper), PVA glue, wire cutters, pliers.

We take 13 pieces of wire according to the number of future branches (70-80 cm each). From one end we leave 5-6 cm and twist to form roots that will go completely into the stand.

We try on our remaining wire on a small bowl to cut to the size we need.

Our roots must be completely placed in the container.

Now we wrap our small bowl with foil (for ease of extraction after the gypsum has completely dried).

We put our roots in a prepared container and fill it with gypsum.

After the gypsum has dried, we remove it from the mold, but do not rush to remove the foil. While we are making branches from wire, the foil will protect the form from chips and damage.

We separate the first three wires and begin to twist them around the barrel. We try to keep the wire tightly pressed against the remaining free pieces of wire.

Having risen 10-15 cm from the roots, we leave the first wire (this is our lower branch), and with the remaining two we continue to wrap the trunk.

Having risen another 1-2 cm, we leave the second wire (this will be the second branch).

Do the same with the third wire. Now we have the first three branches.

Now we take the next three pieces of wire and act with them as with the first. We twist them around the trunk and do not forget to retreat 1-2 cm from each branch.

So gradually we get all the pieces of wire twisted.

We begin to make the length of our branches. The lower ones will be longer than the upper ones.

This is how we should be.

We try on our gypsum blank in size to our main container for the stand. It is necessary that the small one fits completely into the main one.

Now we wrap the main bowl with foil, and remove the foil from the small one.

We place one stand in another. Dilute plaster and pour.

It is better to pour in small portions so as not to miss the amount of gypsum.

After complete drying, the stand is released from the foil.

We take small strips of foil and with their help we begin to form the trunk and roots.

Having achieved the desired result, we proceed to gluing our trunk with a paper towel using PVA glue and a small amount of water.

Together with the trunk, we glue it itself.

Having cut narrow ribbons from a paper towel, we wrap them around the trunk starting from the bottom and gradually rising to the top.

After wrapping, we coat the entire surface with an adhesive solution.

We glue the entire trunk in the same way. The branches themselves remain free. We finish them only after attaching deciduous branches.

We glue the stand for strength with a second layer of paper. For convenience, you can immediately add paint to the glue. It turns out the prepared base.

When the stand is dry, you can move on to its upper part.

We paint the roots and the lower part of the trunk in dark color. For strength, we use a mixture of PVA and paint, as on a stand.

Leftovers can be used to simulate grass. We spread glue on the top of the stand and pour it out.

This is how the stems are obtained. Now you can proceed to the manufacture of the crown. What kind of tree it will be depends only on you. It could be Sakura or Alder. Or maybe you want to make Pine.

It all depends on what branches you attach to your base.